Manufacture of articles

ABSTRACT

The specification discloses a method of making a road wheel for a vehicle in which the material of the wheel has anisotropic properties. The wheel comprises a central portion, a peripheral or rim portion and a plurality of separate radial portions between the central portion and the rim portion. The specification describes how anisotropic properties can be obtained in the radial portions and the peripheral portion by causing the material to flow radially along the radial portions and peripherally around the peripheral portion during the formation of the wheel. This formation is effected by placing a billet of flowable material in a cavity and then moving selected elements of the cavity to produce the desired flow of the material. The wheel can be made of a thermoplastic, synthetic polymeric material with or without fibre reinforcement, a thermosetting, synthetic polymeric material with fibre reinforcement or a metal with or without fibre reinforcement.

[ Aug. 7, 1973 MANUFACTURE OF ARTICLES [75] inventors: Herbert JohnSharp, Greenford;

Margaret Evelyn Norrish, London, both of England [73] Assignee: GKNSankey Limited, Bilston,

England [22] Filed: June 22, 1971 [21] Appl. No.: 155,586

[30] Foreign Application Priority Data June 26, 1970 Great Britain31,088/70 [52] US. Cl. 72/353, 29/159 R, 72/403, 72/413, 264/294,264/322 [51] Int. Cl B2 lj 13/02, B21k 1/32 [58] Field of Search 72/472,352, 403,

Washburn 72/470 Hansen 72/472 Primary Examiner-Charles W. LanhamAssistant Examiner-Gene P. Crosby Attorney-Merriam et al.

[57] ABSTRACT The specification discloses a method of making a roadwheel for a vehicle in which the material of the wheel has anisotropicproperties. The wheel comprises a central portion, a peripheral or rimportion and a plurality of separate radial portions between the centralportion and the rim portion. The specification describes how anisotropicproperties can be obtained in the radial portions and the peripheralportion by causing the material to flow radially along the radialportions and peripherally around the peripheral portion during theformation of the wheel. This formation is effected by placing a billetof flowable material in a cavity and then moving selected elements ofthe cavity to produce the desired flow of the material. The wheel can bemade of a thermoplastic, synthetic polymeric material with or withoutfibre reinforcement, a thermosetting, synthetic polymeric material withfibre reinforcement or a metal with or without fibre reinforcement.

7 Claims, 10 Drawing Figures MANUFACTURE OF ARTICLES BACKGROUND OF THEINVENTION l. Field of the Invention This invention relates to themanufacture of articles, particularly wheels, having a central portion,a peripheral portion and a plurality of separate radial portionsradiating from the central portion to the peripheral portion andinterconnecting the central and peripheral portions.

The invention finds particular utility in the manufacture of road wheelsfor motor vehicles although it is also applicable to the manufacture ofarticles other than road wheels which have continuous or discontinuousperipheral portions and radial portions radiating from a central portionto the peripheral portion.

2. Description of the Prior Art Heretofore, road wheels have been madefrom metal and conventional wheels have been made from steel having aring-like rim which is fixedly or detachably mounted on a disc. Thelighter type road wheels usually comprise a one piece rim welded to adisc. Heavier wheels comprise multipart rims secured to discs. Cast roadwheels of light alloy are also known. In metal wheels it has beenunnecessary to develop any anisotropic mechanical properties in themetal since the normal isotropic properties are sufficiently good towithstand the stresses in use.

It has also been proposed to manufacture road wheels fromfibre-reinforced, synthetic polymeric material by forming wheel halvesby laying up on a mould pieces of glass fibre mat, impregnating these byhand with the polymeric material, allowing the latter to cure and thenfixing the two halves together with, if required, a circumferentiallayer of resin-impregnated reinforcement.

There is a continual search for ways of making, from synthetic polymericmaterial, articles which have previously been made of metal. The methoddescribed above of forming wheel halves with hand laid and impregnatedlayers of glass fibre cloth is not susceptible to the mass production ofwheels. Moreover. since the yield point and ultimate tensile strength ofnormal synthetic polymeric material are less than those of steel it isnecessary to develop the best possible mechanical properties in thematerial to withstand the stresses that occur in use.

In a road wheel embodying the invention the radial portions act asspokes between the central portion which will be the hub and theperipheral portion which will be the rim. The spokes are subjectedmainly to stress in radial directions and therefore it is desirable thatthe best mechanical properties of the material in the spokes areexhibited in radial directions. On the other hand, the rim will besubjected mainly to hoop stress and therefore it is desirable that thebest mechanical properties of the material forming the rim are exhibitedin peripheral directions. The invention has as its object to provide amethod of and apparatus for forming an article having the abovecharacteristics in which the mechanical properties of the material inthe radial portions are improved in radial directions with respect tosuch properties in other directions and in which the mechanicalproperties of the material in the peripheral portion is improved incircumferential directions with respect to such properties in otherdirections.

SUMMARY OF THE INVENTION According to one aspect of the invention weprovide a method of making an article, e.g. a wheel, having a centralportion, a peripheral portion and a plurality of separate radialportions radiating from the central portion to the peripheral portion bycausing flow of flowable material within a cavity having central, radialand peripheral parts in which said central radial and peripheralportions are respectively formed, the method comprising displacing thematerial from the central parts of the cavity into the radial partsthereof and then reducing the volume of said radial parts to causematerial therein to flow radially outwardly and into the peripheral partaround which said material flows peripherally.

The result of this method is to produce an article formed of materialhaving anisotropic properties in both radial portions and the peripheralportion such that the mechanical properties e.g. the yield point, arebetter in radial than other directions in the radial portionsand arebetter in peripheral than other directions in the peripheral portion.

During the first phase of forming in which the material is displacedfrom the central part into the radial parts some material may flow intothe peripheral part but this will be insufficient to fill the peripheralpart which will only be filled when the reduction in size of the radialpart takes place with consequent displacement of material from theradial parts into the peripheral part.

In a preferred way of carrying out the method, during the displacementof the material from the central part of the cavity into the radialparts the peripheral part is held at a larger volume than its finalvolume at which the peripheral portion is formed and the peripheral partis subsequently reduced in size to its final volume simultaneously with,or after, said reduction in size of the radial parts.

This reduction in size of the peripheral part will assist in theperipheral flow of the material in the peripheral part and thus theobtaining of the desired anisotropic properties in the peripheralportion. Preferably the reduction in size of the peripheral part takesplace after the reduction in size of the radial parts has taken place orat least after the reduction in size of the radial parts has commencedthus establishing a flow of material into the peripheral part from theradial parts.

The material from which the article is made is preferably eitherthermoplastic synthetic polymeric material with or without fibrereinforcement or a thermosetting synthetic polymeric material with fibrereinforcement. The reinforcing fibres will be of any convenient materiale.g. carbon or glass. The invention is also applicable to themanufacture of an article by causing metal to flow in the mannerdescribed above and the metal can be fibre reinforced, e.g. withtungsten or boron fibres.

When the material is a thermoplastic synthetic polymeric material, thepolymer chains will be orientated by the flow of the material duringmanufacture of the article so that the chains extend radially in theradial portions and peripherally in the peripheral portions thus givingthe desired anisotropic properties. Where the material, whatever it is,is reinforced with fibres then the fibres will be orientated generallyradially in the radial portions and generally peripherally in theperipheral portions which further assists in obtaining the desiredanisotropic properties. With the cross-linked thermosetting polymericmaterials the anisotropic properties will be obtained by the orientationof the fibre reinforcement.

The material during its flow as the size of the radial parts is reducedwill follow L-shaped paths. Thus during the second forming phase thematerial will be caused to flow radially outwardly along a radial partand then peripherally in the peripheral part. Where the article has acontinuous peripheral portion, e.g. a wheel rim, the material may becaused to flow in generally T- shaped paths. Thus the material may becaused to flow radially outwardly along each radial part and then, whenit reaches the peripheral part, caused to flow peripherally in oppositedirections until the material initially fed along one radial part meetsin the peripheral part, material initially fed radially outwardly alongan adjacent radial part into the peripheral portion.

The areas of the article between the radial portions mentioned above maybe formed by webs in which the material forming them has flowedbiaxially. That is to say that as the material flows outwardly from thecentral part of the cavity it will expand both radially and peripherallyand therefore the polymer chains, metal grains and/or reinforcing fibresas the case may be will be oriented substantially half in radialdirections and substantially half in peripheral directions. Where suchwebs are provided the cavity will include intermediate parts eachdefined between two adjacent radial parts, the central part and theperipheral part. These intermediate parts will be brought to their finalvolume simultaneously with, or before, the first phase of the formingwhen the material is displaced from the central part into the radialparts, the material being simultaneously disposed into said intermediateparts.

In one way of carrying out the method the material is initially in theform of a slug which is deformed and caused to flow between moving partswhich define the cavity and are moved to obtain the desired directionsof flow of the material.

The slug may be formed in situ in the central part of the cavity byinjection.

When the material being formed is a thermoplastic polymeric material ora metal, reduction in size of the mould cavity is arranged to occur atan appropriate time and speed to effect cold work on the material andthus improves the physical properties thereof.

According to another aspect of the invention we produce apparatus forforming from flowable material an article having a central portion, aperipheral portion and a plurality of separate radial portions radiatingfrom the central portion, the apparatus comprising a plurality ofrelatively movable elements which define a cavity having a central part,radial parts and a peripheral part for forming the central, radial andperipheral portions respectively, the elements defining the radial partsbeing movable relative to other/of said elements whereby the radialparts of said cavity may be varied in size independently of other partsof the cavity.

The elements defining the peripheral part of the cavity are movablerelative to other of said elements whereby the movable relative to otherof said elements whereby the peripheral part of the cavity may be variedin size independently of other parts of the cavity.

The cavity includes intermediate parts, each such part being defined bytwo adjacnet radial parts and the central and peripheral parts and theelements defining the intermediate parts are movable relative to otherof said elements whereby the intermediate parts of the cavity may bevaried in size independently of other parts of the cavity.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described indetail by way of example with reference to the accompanying diagrammaticdrawings in which:

FIG. 1 is a section through a cavity showing a billet of material aboutto be deformed by the method of the invention to produce a road wheel;

FIG. 2a is a section through the cavity showing the billet partlydeformed and in a section containing one of said radial parts of thecavity;

FIG. 2b is a section through the cavity corresponding to FIG. 2a but ina section through one of said intennediate parts of said cavity;

FIG. 3 is a section similar to FIG. 2a showing the fianl position of themould elements in a section containing a radial part;

FIG. 4 is a section through the apparatus with the elements in theiropen positions showing the finished wheel ready for ejection;

FIG. 5 is a section through the finished wheel on the line 5-5 of FIG.6;

FIG. 6 is a plan of the wheel of FIG. 5;

FIG. 7 is a section through one of the radial portions of the wheelspokes on the line 77 of FIG. 6; and

FIGS. 8 and 9 are a diagrammatic section and plan respectively ofanother form of apparatus for forming a road wheel embodying theinvention.

Referring first to FIGS. 5, 6 and 7, the wheel comprises a rim orperipheral portion 10 and eight spokelike or radial portions 11. FIG. 7shows that each spoke-like portion 11 is thicker in the axial directionof the wheel than the immediately surrounding or intermediate portions12. These intermediate portions 12 form generally triangular websbetween the adjacent radial portions 11 and are further defined by therim portion 10 and a central or hub portion 13 from which the spokeportions 11 radiate to the rim portion 10.

Referring now to FIG. I, this is a section through the apparatus used toproduce the wheel of FIGS. 5 to 7. There are two annular outer elements14 which form the outer surfaces 15 of the rim, see FIG. 5 and there isa split core element 16 which forms the inner surface 17 of the rim. Thecore element 16 is made in three or more parts to enable it to bewithdrawn from the finished wheel. There is a telescopic shut ofl betweethe elements 14 and 16 constituted by mating surfaces and 16a.

Within each element 14 is an assembly 18 of 16 elements, thus there areeither elements corresponding to the spokes or radial portions 11 andeight elements corresponding to the swebs or intermediate portions 12.The elements corresponding to the spokes can be moved independently ofthe elements corresponding to the webs.

A slug 19 of deformable material is shown between the elements in FIG.I. All the elements in the central assemblies 18 are moved together tocause the material of the slug 19 to flow outwardly from the centralpart 20 of the cavity into the radial parts 21, the intermediate parts22 and the peripheral part 23. The amount of material in the peripheralpart is insufficient to fill it and tis situation is shown in FIGS. 2aand 2b. In FIG.

2a the elements indicated at 24 correspond to the spoke portions 11. InFIG. 2b the elements 25 correspond to the web portions 12. In this firststage of forming the elements 24 are moved to their final positions asshown in FIG. 2b but the elements 24 and 14 are movedonly part way totheir final positions as shown in FIGS. 2a and 2b. The material of theslug 19 which is to form the webs 12 is therefore caused to flowoutwardly into the cavity parts 22 and can expand peripherally due tothe triangular shape of the cavity parts 22 so that the orientation ofthe polymer chains (if a thermoplastic polymer is used) or metal texture(ie the larger grain boundaries and inclusions) and the fibrereinforcement if used is biaxial in the webs 12. That is to say that ifthe material is a thermoplastic plymer approximately half of the chainsare oriented radially and approximately half peripherally. Similarly, ifthe material is metal it will be substantially equally textured inradial and peripheral directions. Any fibre reinforcement will beoriented half radially and half peripherally. The small amount ofmaterial is indicated at 26 which has entered the peripheral cavity part23 within which the rim is to be formed.

In FIGS. 2a and 2b it will be noted that the mould elements l4 and 24are spaced apart by a greater distance than the thickness of thefinished spoke portions 1 l and rim portion respectively but that thefaces 14a and 16a are in engagement thus closing the cavity. Theelements 24 are now closed together as shown in FIG. 3 and this causesthe material in the spoke parts 21 of the cavity to move radially asindicated by the arrow 27 in FIG. 3 and the material enters the cavitypart 23. The material in the cavity part 23 is caused to moveperipherally around the part 23 both by being caused to enter the part23 from the parts 21 and also by the movement of the elements 14together to the positions shown in FIG. 3. The material which flowsradially outwardly from a cavity part 21 flows peripherally around thecavity part 23 until it meets the material flowing from the adjacentcavity part 21. Suitable arrangements are made for venting the cavityparts. It will be seen, therefore, that the flow of material in thespoke cavity parts 21 is generally radial and the flow around the rimcavity part 23 is generally peripheral. This has the effect of producinganisotropic properties as described above with the correspondingadvantages.

FIG. 4 shows the mould open with the core 16 withdrawn and the finishedwheel about to be ejected by ejectors 28.

It will be seen from a consideration of FIG. 6 that the material flow isalong a generally T-shaped path as indicated by the arrows 29 in thatfigure. Alternatively, it could be considered that the material followsa generally L-shaped path i.e. radially along the spoke cavity part andthen peripherally around the rim cavity part.

FIGS. 8 and 9 show a second embodiment of apparatus for producing awheel similar to that shown in FIGS. 5,6 and 7 except that there aretriangular openings between the spoke portions 11 in place of the webs12.

Referring to these figures, the apparatus comprises a lower die element29 which is of generally circular shape in plan and which is formed,around its outer periphery, with an upstanding ring 30 which provides adie shut off face 3]. Immediately within the ring 30 there is an annulardie face 32 shaped to form the outer surface of the rim i.e. the surfacecorresponding to the surface in FIG. 5.

The central part of the element 29 has upstanding therefrom eightgenerally sector shaped abutments 33 which correspond to the spacesbetween adjacent poke or radial portions of the wheel. Between the innerends of the abutments 33 there is defined a central part 34 of the diecavity and fitting closely into this central part is a central element35.

Formed between adjacent abutments 33 are radially cavity parts 36 inwhich the radial portions of the wheel are formed. Moveable in each ofthese radial parts 36 is a radial element 37.

There is a peripheral element 38 having a die face 39 which shapes theother outer surface of the rim and is similar to the die surface 32 andthere are three core members 40 which form the inner surface of the rimin a manner similar to the core members 16 of the first embodiment. Theperipheral element 38 provides a shut off face 41 and the shut off faces31 and 41 cooperate with shut off faces 42 and 43 respectively on thecore elements 40.

In operation, the core elements 40 are moved together to form a ring andthe lower die element 29 is moved upwardly into the position shown inFIG. 8 so that the shut off faces 30 and 31 are in engagement. Theelements 35, 37 and 38 are in their withdrawn positions and a billet ofmaterial is then placed in the central part 34 of the cavity. Theelements 35, 37 and 38 are then moved downwardly, the elements 37,closing the radial parts 36 of the cavity and the element 38 closing theperipheral part 44 of the cavity but the elements 37 and 38 are notmoved to their final positions. The element 35 is moved to its finalposition thus displacing material into the radial part 36 and somematerial into the peripheral part 44. The elements 37 are then moved totheir final positions thus causing radial flow of the material along theradial parts 36 of the mould cavity and simultaneously with orsubsequently with the movement of the die elements 37, the die element38 is moved to its final position thus causing peripheral flow of thematerial around the die cavity 44.

The completed wheel is removed from the cavity by returning the parts totheir open position and ejectors not shown, are used for disengaging thewheel from the elements.

The material which may be used for carrying out the method in eitherembodiment may be a synthetic polymeric material or a metal. In theformer case, if the polymeric material is thermoplastic then theanisotropic properties desired are obtained both by orientation of thepolymer chains and, if fibre reinforcement is present, orientation ofthe fibres of the reinforcement. Thus the chains and the reinforcementif provided will be oriented generally radially in the spoke or radialparts 11 of the finished wheel and the polymer chains and or fibrereinforcement if provided will be.

oriented peripherally in the rim part of the finished wheel. If thesynthetic polymeric material is a thermosetting material then there willbe no orientation of the polymer chains since of course cross linkingoccurs but with a termosetting polymeric material it will be reinforcedwith a fibre reinforcement and the orientation of the reinforcement willbe radial in the spoke portions of the wheel and peripherally in theperipheral portions of the wheel.

If the material used for making the wheel is metal then the grainboundaries will be oriented as described and if fibre reinforcement isused then the reinforcing fibres will also be oriented in the requiredmanner.

It is not necessary that the peripheral part of the cavity be variablein size except for the purpose of course of opening the cavity. Thus ina modification of the method, the peripheral part of the cavity may bebrought to its final size with the first phase of the forming i.e. inthe phase illustrated in FIGS. 2a and 2b. The overall flow of thematerial around the peripheral part of the cavity would, in such anarrangement, be obtained by the radial displacement of the material fromthe radial parts of the cavity into the peripheral part thereof.

Where the peripheral part of the cavity can be changed in size then thischange in size can either be caused to occur simultaneously with themovement of g the mould elements 24 to their final positions orsubsequently to such movement. Preferably, the peripheral part of thecavity is brought to its final size at least after the commencement ofthe movement of the parts 24 to their final size so that such movementof the parts 24 establishes a flow of material into the peripheral partof the cavity before the latter is brought to its final size.

The invention has been described in relation to a road wheel having acontinuous rim but obviously a similar method can be followed for awheel or similarly shaped article having a discontinuous rim.

We claim:

1. A method of making an article having a central portion a peripheralportion and a plurality of separate radial portions radiating from thecentral portion to the peripheral portion by causing flow of flowablematerial within a cavity having central, radial and peripheral parts inwhich said central, radial and peripheral portions are respectivelyformed, the method comprising displacing material from the central partof the cavity into the radial parts thereof and then reducing the sizeof said radial parts to cause material therein to flow radiallyoutwardly into the peripheral part around which the material flowsperipherally.

2. A method according to claim 1 wherein, during the displacement of thematerial from the central part of the cavity into the radial partsthereof, the peripheral part of the cavity is held at a larger volumethan its final volume at which the peripheral portion is formed and theperipheral part is subsequently reduced in size to its final volume,said reduction commencing no earlier than said reduction in size of theradial parts.

3. A method according to claim 2 wherein said reduction in size of theperipheral part of the cavity takes place after the reduction in size ofthe radial parts.

4. A method according to claim 1 wherein the material fiows in T-shapedpaths from the radial parts of the cavity into the peripheral partthereof.

-5. A method according to claim 1 including the step of forming, betweenadjacent radial portions, webs by causing the material to flow biaxiallyinto intermediate cavity parts between the radial cavity parts.

6. A method according to claim 5, wherein the cavity includesintermediate parts each defined between two adjacent radial parts, thecentral part and the peripheral part and wherein the method is carriedout by bringing the intermediate parts to their final volumes no laterthan the displacement of the material from the central part into theradial parts, the material being simultaneously displaced into saidintermediate parts.

7. Apparatus for forming from flowable rnaterial an article having acentral portion, a peripheral portion, a plurality of separate radialportions radiating from the central portion, and aplurality ofintermediate portions each defined between two adjacent radial portionsand the central and peripheral portions the apparatus comprising aplurality of relatively movable elements which define a cavity having acentral part, radial parts, a peripheral part and intermediate parts,each intermediate part being defined by two adjacent radial parts andthe central and peripheral parts, for forming the central, radial,peripheral and intermediate portions respectively, the elements definingthe radial parts being movable relative to other of said elementswhereby the radial parts of said cavity may be varied in sizeindependently of the other parts of the cavity, the elements definingthe peripheral part of the cavity being movable relative to other ofsaid elements whereby the peripheral part of the cavity may be varied insize independently of the other parts of the cavity, and the elementsdefining the intermediate parts being movable relative to other of saidelements whereby the intermediate parts of the cavity may be varied insize independently of the other parts of the cavity.

1. A method of making an article having a central portion a peripheralportion and a plurality of separate radial portions radiating from thecentral portion to the peripheral portion by causing flow of flowablematerial within a Cavity having central, radial and peripheral parts inwhich said central, radial and peripheral portions are respectivelyformed, the method comprising displacing material from the central partof the cavity into the radial parts thereof and then reducing the sizeof said radial parts to cause material therein to flow radiallyoutwardly into the peripheral part around which the material flowsperipherally.
 2. A method according to claim 1 wherein, during thedisplacement of the material from the central part of the cavity intothe radial parts thereof, the peripheral part of the cavity is held at alarger volume than its final volume at which the peripheral portion isformed and the peripheral part is subsequently reduced in size to itsfinal volume, said reduction commencing no earlier than said reductionin size of the radial parts.
 3. A method according to claim 2 whereinsaid reduction in size of the peripheral part of the cavity takes placeafter the reduction in size of the radial parts.
 4. A method accordingto claim 1 wherein the material flows in T-shaped paths from the radialparts of the cavity into the peripheral part thereof.
 5. A methodaccording to claim 1 including the step of forming, between adjacentradial portions, webs by causing the material to flow biaxially intointermediate cavity parts between the radial cavity parts.
 6. A methodaccording to claim 5, wherein the cavity includes intermediate partseach defined between two adjacent radial parts, the central part and theperipheral part and wherein the method is carried out by bringing theintermediate parts to their final volumes no later than the displacementof the material from the central part into the radial parts, thematerial being simultaneously displaced into said intermediate parts. 7.Apparatus for forming from flowable material an article having a centralportion, a peripheral portion, a plurality of separate radial portionsradiating from the central portion, and a plurality of intermediateportions each defined between two adjacent radial portions and thecentral and peripheral portions the apparatus comprising a plurality ofrelatively movable elements which define a cavity having a central part,radial parts, a peripheral part and intermediate parts, eachintermediate part being defined by two adjacent radial parts and thecentral and peripheral parts, for forming the central, radial,peripheral and intermediate portions respectively, the elements definingthe radial parts being movable relative to other of said elementswhereby the radial parts of said cavity may be varied in sizeindependently of the other parts of the cavity, the elements definingthe peripheral part of the cavity being movable relative to other ofsaid elements whereby the peripheral part of the cavity may be varied insize independently of the other parts of the cavity, and the elementsdefining the intermediate parts being movable relative to other of saidelements whereby the intermediate parts of the cavity may be varied insize independently of the other parts of the cavity.